Machines for throwing balls which accelerate the ball through the use of two opposed spinning wheels, such as shown in WILSON, U.S. Pat. No. 2,729,206, DOEG, U.S. Pat. No. 2,918,918, YARUR, et al., U.S. Pat. No. 3,913,552, HALSTEAD, U.S. Pat. No. 3,724,437 and BETTEN, U.S. Pat. No. 3,811,421, are relatively expensive due to the increasing cost of the special tires involved in such machines and the need for special transmission or multiple motors. Single-wheel machines, that is machines which accelerate the ball by using a single wheel opposed by some sort of chute, usually having a rub strip therein, are more economical to manufacture but suffer from poor accuracy and the inability to accelerate a ball to as fast a speed as the two-wheel machines. There are instances where, for example, the single-wheel ball-throwing machine is to be used to provide softball batting practice, slow pitch softball batting practice or baseball practice for up to 12 year old individuals where this inability to highly accelerate a ball is not of major disadvantage. However, for such applications, the accuracy of the throw becomes more important since the participants are usually less skilled in avoiding an errant throw. In some single-wheel machines, complex control mechanisms have been employed to attempt to improve the accuracy of the machines. Heretofore these attempts have not been particularly successful. In addition, complex control mechanisms are expensive which eliminates the cost advantage that would otherwise exist between such single-wheel and the double-wheel machines.